EDIT: I forgot to preface this by saying that this is exciting work so far. Thanks for showing it off!
Wait, you showed a tailcap draw of 4.2A earlier. I don’t think we’re looking at 97 efficiency here… more like 65% efficiency, right?
Here are my assumptions:
Output = 1.5A @ 6.4v = 9.6W
Input = 4.2A @ 3.5v = 14.7W~
Efficiency = 9.6W / 14.7W = 0.65 = 65%
I take it that this design is CV then?
IIRC that’s the direction Lamdba went with the boost driver for VaraPower lights. It was a fairly different situation, but my understanding was that the driver worked well and provided a lot of power. If you are interested I think that the best information on that driver is available over here, starting with post #20.
It helps me! Thanks for posting the link, but don’t forget to include the post # since BLF’s forum software doesn’t behave nicely with direct links depending on your “view” settings. FWIW that’s Post #1616 over there.